This is a proposal for continuing studies of neurogenic hypertension in the rat induced by sinoaortic denervation, (SAD). Major objectives are to delineate plasma and tissue indices that reflect the state of sympathetic nervous activity and to determine which processes develop in the course of time to alter these indices. Specific studies will: 1) test the hypothesis that degradative enzyme activity and catecholamine metabolites increase in tissues and blood in the course of SAD hypertension and, 2) estimate degree of participation of the renin-angiotensin system. Additional aims are: 1) to identify biochemical changes in specific brain cells of SAD rats and 2) to determine the central cerebellar nuclei that might contribute to arterial pressure lability in SAD rats and 3) to investigate participation of vasopressin in the course of SAD hypertension with special reference to the venous side of the circulation.